Mineral oil composition



Patented Apr. 14, 1936 UNITED STATES PATENT OFFICE MINERAL OILCOMPOSITION No Drawing. Application June 7, 1933, Serial No. 674,695

1 Claim.

This invention relates to the production of lubricating oils with lowpour points.

It is known that the pour point of a lubricating oil of ordinarycomposition is determined, in

5 part, by the content of waxy materials dissolved in the liquidhydrocarbons, and that at a critical low temperature these waxymaterials separate in crystals which interfere with the fluid movementof the oil. It is also known that the pour point of an oil containingwaxy material may be lowered by the addition of a small quantity of somematerial, dissolved in the oil, which modifies the normalcrystallization of the waxy material.

The present invention resides in the discovery that a material suitablefor use as a pour point depressant may be derived from adsorbent earthwhich has been utilized in the filtration of the unrefined residue ofpetroleum distillation com.

monly described as cylinder stock. The chemical composition of thematerial so derived is complex and varies with the character of thecylinder stock, and it has not yet been ascertained to which constituentor constituents the value as a pour-point depressant is to beattributed. However, it has been found sufiicient, for practicalpurposes, to use without separation the material or materials which canbe derived from the adsorbent earth by means of a solvent such asethanol, or a mixture of ethanol and chloroform, after the clay has beenwashed with a volatile petroleum solvent such as petroleum ether ornaphtha.

A satisfactory method for the production of the material in question isas follows: adsorbent earth which has been used, in the ordinary manner,for the filtration of a high-viscosity steam-refined cylinder stock, isfirst washed with petroleum ether, until the washings are practicallyfree from oil. The earth is then washed with a mixture of chloroform andethanol until substantially all of the material removable by thismixture has been extracted. From this second solution the solvents arethen removed by distillation,

leaving the tarry viscous material which is .desired. The. solution of asmall percentage of this material in a Wax-containing refinedlubricating oil of moderate viscosity will substantially lower the pourpoint of the oil. 5

As a specific example of the use of this pourpoint depressant, it wasadded to a refined petroleum lubricant stock having a Saybolt universalviscosity, at 210 F., of seconds. Before the addition of the depressant,the pour 10 point of the oil was 30 F. The addition of the depressant inan amount equal to 2% of the weight of the oil lowered the pour point to0 F., while the addition of 5% lowered the pour point to -.15 F. v

The quantity of depressant required for definite results depends uponthe character of the lubricant stock, particularly with regard to itsviscosity and its wax content. An oil of high viscosity and low waxcontent may be afiected 20 little or not at all by the addition of adepressant, while an oil of low viscosity and high wax content will bemost susceptible to the use of the depressant.

The pour-point depressant with which this in- 25 vention is concernedmay be derived from the adsorbent earth and separated from undesirablematerial by the use of various combinations of solvents, and the mentionof particular solvents in the specification and the claim is intended 30merely to identify the material, but not to limit the invention to anyparticular method of deriving it from the adsorbent earth.

The invention claimed is:

The combination, with a refined petroleum lu- 35 bricant stockcontaining waxy material, of an' amount, suflicient to lowersubstantially the ,pour point of said stock, of that part, exclusively,of the material adsorbed from residual cylinder stock by adsorbentearth, which is removable 40 from said earth by washing with ethanol butnot by washing with petroleum ether.

HARRY A. CURTIS.

